Substances such as industrial ashes and incineration ashes have so far been passed on mainly as waste for utilization primarily to the building and cement industries.
Owing to the material property of starting materials such as ashes, which have a large proportion of important components such as CaO, MgO, Al2O3 and Na2O, the recycling of waste products to basic products that can be reintroduced into industrial processes e.g. in paper and wood processing or in ground stabilization is of economic and ecological interest.
DE 10 2005 029500 A describes that by the indirect use of the high alkali and alkaline earth oxide contents a substitution of soda lye by recycled ash as alkalizing agent is used in paper recycling and in wood pulp bleaching.
Conventional methods have so far been used for recycling starting materials such as ashes, in particular milling in a wet process with conventional milling machines such as ball mills. In the conventional wet milling methods, however, technical problems and high downtime often arise, which are caused by the abrasive wear of the milling tools or blockings of the plant. A further problem of wet milling is that the process takes place under atmospheric conditions and a reaction takes places directly during milling. With the conventional milling machines, however, dry processes cannot be used owing to cakings and blockings in the milling machines, although the dry process would be better by far for the use of the basic products e.g. in order to be able to avoid subsequent drying processes.
Moreover, it has been found that in the conventional methods, a defined particle size and a high reactivity of the basic products cannot be reached or can only be reached with a high expenditure of energy. Therefore, the recycling of starting materials such as industrial ashes and incineration ashes has been uneconomic so far due to the high amount of energy required.
Furthermore, basic products produced with conventional methods tend to agglomerate and form aggregates, which results in that no defined particle size is reached, the basic products have a low reactivity and consequently, due to the low quality, can only be reintroduced into industrial processes to a limited extent.
These circumstances have so far prevented efficient recycling of a plurality of starting materials for use as a marketable basic product and further processing thereof to an end product.